Openwork design for seat backs



FIG. 1 is a rear elevational view showing my new design, the front viewbeing mirror image thereof;

FIG. 2 is a right side elevational view thereof, the left side being amirror image thereof;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a bottom plan view thereof.

The ornamental design for an openwork design for seat backs, as shownand described.